Can specify project options on the command line and the override defaults.

environment.py

@@ -1376,6 +1376,7 @@ class Environment():
             self.cross_info = CrossBuildInfo(self.coredata.cross_file)
         else:
             self.cross_info = None
+        self.cmd_line_options = options.projectoptions
 
         # List of potential compilers.
         if is_windows():

interpreter.py

@@ -639,7 +639,8 @@ class Interpreter():
         self.source_root = build.environment.get_source_dir()
         option_file = os.path.join(self.source_root, self.subdir, 'meson_options.txt')
         if os.path.exists(option_file):
-            oi = optinterpreter.OptionInterpreter(self.subproject)
+            oi = optinterpreter.OptionInterpreter(self.subproject,\
+                                                  self.build.environment.cmd_line_options)
             oi.process(option_file)
             self.build.environment.merge_options(oi.options)
         mesonfile = os.path.join(self.source_root, self.subdir, environment.build_filename)

meson.py

@@ -70,6 +70,8 @@ parser.add_option('--werror', action='store_true', dest='werror', default=False,
                   help='Treat warnings as errors')
 parser.add_option('--cross-file', default=None, dest='cross_file',
                   help='file describing cross compilation environment')
+parser.add_option('-D', action='append', type='string', dest='projectoptions', default=[],
+                  help='Set project options.')
 
 class MesonApp():
 

optinterpreter.py

@@ -39,6 +39,9 @@ class UserOption:
         super().__init__()
         self.description = kwargs.get('description', '')
 
+    def parse_string(self, valuestring):
+        return valuestring
+
 class UserStringOption(UserOption):
     def __init__(self, kwargs):
         super().__init__(kwargs)
@@ -59,6 +62,13 @@ class UserBooleanOption(UserOption):
             raise OptionException('Value of boolean option is not boolean.')
         self.value = newvalue
 
+    def parse_string(self, valuestring):
+        if valuestring == 'false':
+            return False
+        if valuestring == 'true':
+            return True
+        raise OptionException('Value %s is not a boolean.' % valuestring)
+
 class UserComboOption(UserOption):
     def __init__(self, kwargs):
         super().__init__(kwargs)
@@ -83,10 +93,14 @@ option_types = {'string' : UserStringOption,
                 }
 
 class OptionInterpreter:
-    def __init__(self, subproject):
+    def __init__(self, subproject, command_line_options):
         self.options = {}
         self.subproject = subproject
-    
+        self.cmd_line_options = {}
+        for o in command_line_options:
+            (key, value) = o.split('=', 1)
+            self.cmd_line_options[key] = value
+
     def process(self, option_file):
         try:
             ast = mparser.Parser(open(option_file, 'r').read()).parse()
@@ -159,4 +173,6 @@ class OptionInterpreter:
         opt = option_types[opt_type](kwargs)
         if opt.description == '':
             opt.description = opt_name
+        if opt_name in self.cmd_line_options:
+            opt.set_value(opt.parse_string(self.cmd_line_options[opt_name]))
         self.options[opt_name] = opt

readme.txt

@@ -4,8 +4,8 @@ build system.
 
 Dependencies
 
-Python 3.3: http://python.org
-Ninja:      http://martine.github.com/ninja/
+Python   http://python.org (version 3.3 or newer)
+Ninja    http://martine.github.com/ninja/
 
 
 Installing from source